1. Field of the Invention
The invention relates to method and apparatus for the casting of metals. It specifically relates to methods and apparatus systems for automatic casting of metals, particularly non-ferrous metals such as zinc, aluminium, tin, lead and alloys. More specifically the invention relates to methods and apparatus for casting metal ingots, especially jumbo ingots.
2. Description of Related Art
In metal refining it is often necessary to transport raw material from place to place so it may be delivered to a facility where it can be reworked into an eventual end product. One easily transported form is a foundry ingot. Therefore, it is common to form metal into foundry ingots for the purpose of shipping and transportation to end users. Such end users they may use the foundry ingots as feed stock for a further operation.
It is known from the prior art e.g. CA 2,240,332 a system for the automatic casting of metals, especially zinc, which includes a four station indexing carousel for indexing moulds. The stations are casting station, where metal is cast via a launder, a skimming station where an automatic robot controlled skimmer removes dross, a transfer station from which moulds containing molten metal are removed by an overhead crane to be placed in a cooling tank and cooled moulds containing the solidified ingot are returned by the crane to the transfer station of the carousel, and a delivery station where the cast ingots are removed from the moulds by another overhead crane. The empty moulds are recycled to the casting station. This system lay-out and its product flow are rather complicated. The cooled mould with the solidified ingot is returned from the cooling tank to the casting carousel. Thus the mould is placed in the transfer station two times in a working cycle before the solidified ingot is removed. The ingot is removed at the delivery station of the indexing carousel. The delivery station and the casting station are very near each other. This can be hazardous to the operation personnel. Furthermore the product flow of cast jumbo ingots is complex. Moreover, the fast movements of the overhead crane, when moving the mould with molten metal, can lead to the decreased quality of the ingot surface.
The object of the present invention is to realize a method and apparatus for casting metal ingots, by means of which the drawbacks of the prior art are avoided. Another object of the invention is to achieve a casting method and apparatus that is more effective than those of the prior art. Likewise, an object of the invention is to realize a method and apparatus that is better suited for the casting of jumbo ingots than the prior art arrangements.
The invention is characterized by what is set forth in the appended claims. The method according to the invention is characterized, among others, in that the method for the casting of metals comprising the steps of: indexing a mould in series on a rotating carousel to a pouring station, skimming station and a mould transfer station; casting molten metal into the mould at the pouring station; skimming dross from the molten metal at the skimming station; transferring the mould containing molten metal from the mould transfer station to a cooling section and replacing it at the mould transfer station with an empty mould; transferring a cooled mould containing a solidified metal ingot from the cooling section to a demoulding station remote from the rotating carousel; removing the solidified ingot from the mould; removing the pin/hook members from the ingot; returning the pin/hook members to the empty mould; returning the empty mould to the mould transfer station; and transferring the ingot to the further processing.
An embodiment of the method according to the invention is characterized in that the mould is transferred by a transfer car and/or by lifting device from mould transfer station to the cooling section. An embodiment of the method according to the invention is characterized in that the empty mould is returned to the mould transfer station by a transfer car. The mould with molten metal is transferred from the transfer car to a cooling chamber of the cooling section by a lifting device. The ingot is further transferred from the demoulding station to a pin/hook member removal station. The pin members are removed by pushing the pin members from the ingot. The cooling section is located between the carousel and the demoulding station. The transfer car is moved on a track between the carousel and the demoulding station. The cooled mould containing the ingot is transferred from cooling chamber to the demoulding station by the lifting device, especially by a crane device.
The apparatus for casting metal ingots according to the invention, comprises:
a feed system for delivering molten metal to be cast;
an indexing carousel at the end of feed system for indexing moulds provided thereon, comprising:
a pouring station for pouring molten metal into a mould;
a skimming station for skimming dross from the surface of molten metal;
a mould transfer station for transferring the mould with molten metal from indexing carousel and replacing it with an empty mould; and
drive means for rotating the carousel;
transfer means for transferring the mould with molten metal from the mould transfer station of the carousel to a cooling section and returning the empty mould back to the mould transfer station of the carousel;
a cooling section, comprising a plurality of cooling chambers;
a demoulding station, for removing a solidified ingot from the mould;
and means for transferring ingot to further processing.
A preferred embodiment of the apparatus according to the invention is characterized in that the transfer means comprise a transfer car and a crane device. The apparatus further comprises a pin and/or hook member removal station located at or after the demoulding station. The pouring station comprises means for moving the mould in vertical direction. The skimming station is provided with means for automatic skimming of dross from molten metal contained in the mould. The indexing carousel is provided with cradles to hold moulds. The feed system comprises a pouring tundish for delivering molten metal to a mould at the pouring station and a stopper rod means for opening and closing a pouring orifice of the tundish. The stopper rod means comprise control means and measuring means of the level of metal in the mould and/or measuring means of the tundish level. A shuttle car is provided to transfer the empty mould between demouding station and the pin/hook removal station.
The casting method and the apparatus according to the invention have several remarkable advantages. The demolding and ingot discharge zone is well away from the actual molten metal pouring station, which promotes a better flow of ingots out of system and is less hazardous for the operation personnel. The lay-out of the system according to the invention is shorter than the prior art system for given production rate. Moreover the system according to the invention permits slower overhead crane movements for the mould with molten metal, which promotes smoother ingot surface finish. Furthermore, the three position carousel reduces space required around the pouring zone and furnace and reduces any man power requirements in this area. In addition the three station carousel allows the continuation of the pouring operation if demolding operation stops for any reason.